Cellulose mixed ester sheeting containing a lower alkyl myristate



Patented Aug. 9, 1938 PATENT QFFIQE CELLULOSE MIXED ESTER SHEETING CON-TAINING A LOWER ALKYL MYRISTATE Henry B. Smith, Rochester, N. Y.,assignor, by mesne assignments, to Eastman Kodak Com pany, Jersey City,N.

Jersey J., a corporation of New No Drawing. Application December 26,1935, Serial No. 56,237

3 Claims.

This invention relates to plasticizers for mixed organic acid esters ofcellulose, such, for instance, as cellulose acetate-propionate,cellulose acetatebutyrate, cellulose acetate-stearate and the like. Oneobject of the invention is to provide cellulose mixed ester compositionsfrom which flexible sheets and other useful plastic products may bemade. Another object is to provide flexible sheets of cellulose mixedesters, such as are useful for photographic film, wrapping sheets, etc.Other objects will hereinafter appear.

Cellulose acetate-propionate has become known only within the last fewyears, and the field of plasticizers for it and for other mixed estersof cellulose is, as yet, not well explored, although certainplasticizers for these esters have recently been discovered, such, forinstance, as tri-o-diphenyl phosphate, diamyl hydroquinone, monobutylglyceryl oleate, ethoxyethyl laurate, diacetyl glyceryl stearate,ethoxyethyl stearate, ethylene glycol dilaurate and chlorinated paraffinoil.

Fully esterified cellulose acetate-propionate, celluloseacetate-butyrate, etc., may be prepared as described in Clarke and MalmsU. S. Patent No. 1,800,860. The preparation of partially hydrolyzedcellulose acetate-propionate and other mixed esters, i. e., celluloseacetate-propionate, etc., from which a portion of the acyl groups hasbeen hydrolyzed off, is described in the co-pending application of CarlJ. Malm and Charles E. Fletcher Serial No. 551,546, Patent No.2,026,583. Cellulose acetate-stearate may be prepared as described inClarke and Malms U. S. Patent No. 1,987,053.

Cellulose acetate-propionate, acetate-butyrate, etc. have propertiesdiffering from those of cellulose acetate. For instance, propylenechloride and ethylene chloride, which alone are not solvents forcellulose acetate-either fully esterified or partiallyhydrolyzed-readily dissolve a majority of these cellulose esters,whether fully esterified or partially hydrolyzed, and sheets coated fromsuch solutions, even without a plasticizer, show fair flexibility, as isdisclosed in Carl J; Malms U. S. Patent No. 2,006,362. Furthermore,acetone is a solvent for unhydrolyzed or fully esterified celluloseacetate-propionate, although sheets coated from such solutions arebrittle, whereas unhydrolyzed cellulose acetate is not soluble inacetone.

Consistently with the unexpected behavior of the cellulose mixed esters,I have now found that certain compounds which are scarcely compatiblewith commercial forms of cellulose acetate are excellent plasticizersfor cellulose acetate-pro pionate, cellulose acetate-butyrate, etc. Thelower alkyl myristates, such as methyl and ethyl myristates, while theymay be compatible with cellulose nitrate, are incompatible with the onlycommercially-used form of cellulose acetate, namely, acetone-solublecellulose acetate, and consequently, nowhere in the art have they everbeen suggested as components of celluloseacetate compositions. Contraryto expectation, I have discovered that the lower alkyl myristates, suchas methyl and ethyl mryistates, are compatible with, and excellentplasticizers for, both fully esterified and partially hydrolyzedcellulose mixed organic acid esters, such as celluloseacetatepropionate, cellulose acetate-butyrate, celluloseacetate-stearate, etc. The ratio of ,acetyl radical to higher fatty acidradical in the cellulose mixed ester may be varied within wide limits.

In order that those skilled in the art may better understand myinvention I would state, by way of illustration, that for themanufacture of photographic film base or other sheets my newcompositions of matter may be compounded as follows: parts by weight ofsubstantially fully esterified cellulose acetate-propionate is dissolvedwith stirring in from 500 to 600 parts by weight of ethylene chloride.To this solution may be added from 5 to 30 parts by weight, or evenmore,

of methyl myristate or ethyl myristate. Within the limits stated, theamount of plasticizer may be decreased or increased, depending uponwhether it is desired to decrease or increase, respectively, theproperties which these plasticizers contribute to the finished product.The amount 5 of solvent employed may also be increased or decreased,depending upon whether it is desired to have a more or less freelyflowing composition, respectively.

A composition of matter prepared as above described may be depositedupon any suitable filmforming surface to form a film or sheet, in amanner well known to those skilled in the art. A film so produced haspermanently brilliant transparency and low infiammability, burning nomore readily than ordinary newsprint. Films or sheets produced inaccordance with my invention are tough and extremely flexible. Forinstance, films of fully esterified cellulose acetate-propionateplasticized with from 10% to 30% of methyl myristate (parts by weightbased on the weight of the cellulose ester) had an initial flexibilityof from 300% to 560% of that of a film of the same cellulose ester withno plasticizer, and films of fully esterified celluloseacetate-propionate P sults.

plasticized with from 10% to of ethyl myristate had an initialflexibility of from 320% to 680% of that of a film of the same celluloseester with no plasticizer.

Furthermore, films plasticized with my novel plasticizers maintainflexibility in a superior fashion. For instance, a film of fullyesterified cellulose acetate-propionate containing 20% of methylmyristate (20 parts by weight of methyl myristate per 100 parts ofcellulose ester) retained flexibility at C. for 114 days, and filmscontaining from 20 to 30% of ethyl myristate or 30% of methyl myristateretained flexibility for 121 days, whereas an unplasticized film of thesame cellulose ester had become brittle at the end of '72 days. Thisindicates that film so plastlcized will withstand ordinary usagesatisfactorily for many years.

Other solvents which are compatible with the cellulose ester being used,and with the plasticlzer, may be employed instead of those mentionedabove. Other mixed esters of cellulose, such, for instance, as celluloseacetate-butyrate and cellulose acetate-stearate, showed similar re-Partially hydrolyzed mixed esters showed results similar to those shownby the fully esterifled esters.

While I have described the manufacture of films and sheets from my newcompositions, it

will be apparent that they may be employed with advantage in the otherbranches of the plastic art, such, for instance, as in the manufactureof lacquers.

What I claim as my invention and desire to be secured by Letters Patentof the United States 1s:

1. A transparent, flexible sheet comprising parts by weight of acellulose mixed organic acid ester selected from the group consisting ofcellulose acetate-propionate, cellulose acetate-butyrate and celluloseacetate-stearate and, as a plasticizer therefor, from 5 to 30 parts byWeight of a lower alkyl myristate.

2. A transparent, flexible sheet comprising 100 parts by weight of acellulose mixed organic acid ester selected from the group consisting ofcellulose acetate-propionate, cellulose acetate-butyrate, and celluloseacetate-stearate and, as a plasticizer therefor, from 5 to 30 parts byweight of methyl myristate.

3. A transparent, flexible sheet comprising 100 parts by Weight of acellulose mixed organic acid ester selected from the group consisting ofcellulose acetate-propionate, cellulose acetate-butyrate and celluloseacetate-stearate and, as a plasticizer therefor, from 5 to 30 parts byweight of ethyl myristate.

HENRY B. SMITH.

